Update schema.rb to correct problem "ActiveRecord::StatementInvalid:...

Update schema.rb to correct problem "ActiveRecord::StatementInvalid: Mysql2::Error: BLOB/TEXT column 'tags' can't have a default value:" when we migration on mysql database

db/schema.rb

@@ -66,7 +66,7 @@ ActiveRecord::Schema.define(version: 20180408212139) do
     t.string "contact", limit: 255, default: ""
     t.string "submitter", limit: 255, default: "", null: false
     t.integer "moderated", limit: 4, default: 0, null: false
-    t.text "tags", limit: 255, default: ""
+    t.text "tags", limit: 255, null: true
     t.string "secret", limit: 255, default: "", null: false
     t.datetime "decision_time"
     t.datetime "submission_time"
@@ -119,7 +119,7 @@ ActiveRecord::Schema.define(version: 20180408212139) do
     t.datetime "created_at"
     t.datetime "updated_at"
     t.text "tag"
-    t.text "tags", default: ""
+    t.text "tags", null: true
     t.text "diaspora"
     t.text "object_changes"
     t.text "place_name"